The heat treatment system: steel bar annealing, wire annealing or 830-840 degrees oil quenching.
Heat treatment process parameters:
1. Normal annealing: 790-810 degrees heating, the furnace cooled to 650 degrees, the air-cooled - HB170-207
2. Isothermal annealing: 790-810 degrees heating, 710-720 degrees isothermal, air-cooled - HB207-229
3. Normalizing: 900-920 degrees heating, air cooling - HB270-390
4. High temperature tempering: 650-700 degrees heating, air cooling - HB229-285
5. Quenching: 860 degrees heating, oil quenching - HRC62-66
6. Low temperature tempering: 150-170 degrees tempering, air cooling - HRC61-66
7. Carbonitriding: 820-830 degrees co-permeate 1.5-3 hours, oil quenching, -60 degrees to -70 degrees cryogenic treatment +150 degrees to +160 tempering, air cooling - HRRC67
The quality of the bearing steel is very high, and it is necessary to strictly control the content and distribution of sulfur, phosphorus and non-metallic inclusions because the content and distribution of non-metallic inclusions have a great influence on the life of bearing steel. The higher the amount of inclusions, the shorter the life span. In order to improve the quality of smelting, has recently been used electric furnace smelting and electroslag remelting, can also use vacuum smelting, vacuum consumable refining and other new technology to improve the quality of bearing steel.
The main purpose
For the production of various bearing rings and rolling elements, such as: the production of internal combustion engines, electric locomotives, automobiles, tractors, machine tools, rolling mills, drilling machines, mining machinery, general machinery, and high-speed rotation of a high load mechanical transmission bearing steel Balls, rollers and rings. In addition to balls, bearing rings, etc., sometimes used to manufacture tools such as dies and gauges.
6. Chemical composition of the national standard, the standard, the Japanese standard in the chemical composition of the main steel in Table 6-7-24.
Table 6-7-24 Chemical composition indicators for major steel grades in the relevant standards
Standard No. Steel Chemical composition% C Si Mn P S Cr Mo Ni
GB/T3086 -82 9Cr18 0.90- 1.00 <0.80 <0.80 <0.035 <0.030 17.00- 19.00
GB/T3203 -82 G20 CrMo 0.17- 0.23 0.20- 0.35 0.65- 0.95 <0.030 <0.030 0.35- 0.65 0.08- 0.15
YB(T)1 -91 GCr15 0.95- 1.05 0.15- 0.35 0.25- 0.45 <0.025 <0.025 1.40- 1.65 <0.30
JISG4805 -90(96) SVJI 0.95- 1.10 0.15- 0.35 <0.50 <0.025 <0.025 0.90- 1.20 <0.25